It must be ever so vexing to pass a law that you think will make you the most popular boy in class – only to be greeted by a mass chorus of “you still stink!”.

That seems to have been the case with the abolition of the 10p rate of tax, and it may yet come to pass with government legislation on extreme porn.

Of course, it isn’t law yet. The Criminal Justice Bill – of which it is part - receives the Royal Assent tomorrow (8 May). But the sections on extreme porn only become operative on their allotted commencement date. That has not yet been set.

In fact, it may never be set. One unhappy feature of this government’s approach to law-making is that some laws are passed, and then forgotten, without ever being put into effect.

Could that happen with extreme porn? Or at least, with this incarnation of the law?

The last few days have seen a step change in responses to the legislation. One straw in the wind has been the large and overwhelmingly hostile postbag I have received since starting to write more widely on this issue. (Hostile to the law, that is, not to me.)

Men are getting cross. Women, too. But it is the men who are significant. Men tend not to politicise, as a group, around single issues. They seem to be doing so now. And whilst a mass movement of men dedicated to preserving their right to wank fodder may not be the most edifying of sights, it is still powerful.

The government has claimed that this law will only affect a tiny minority of individuals. In response, the Lords objected time and time again that the definitions were too wide and that individuals would not be able to tell what was legal, what not. In the confines of the debating chamber, this was an interesting abstract argument.

When it becomes a real question of whether or not possessing a certain picture could have you jailed for up to three years, all abstraction quickly fades.

This ambiguity has not been lost on campaigners against the law, who today moved from arguing the case, to direct action. A small group met outside the British Library this morning to burn images taken from a range of “coffee table” books. It was a symbolic gesture. The images may be illegal when the “Dangerous Pictures Act” – as they now describe the extreme porn provisions – becomes law. They may not. As the demonstrators themselves said: “Who knows?”

One of the books from which pictures were taken was Sex by Madonna. It's a controversial and collectible tome. On Amazon today, a mint edition was being offered for £700.

I spoke to five different lawyers and got five different views. Three thought the book would be in the clear. Two thought it contained images that could breach the new law.

Other books likely to cause problems include works by noted photographers Robert Mapplethorpe and China Hamilton.

Of course, the government will utter soothing words. But in a world in which possessing the wrong image could now make you a criminal, there will inevitably be a tendency towards caution. So there is crossness. And there is fear.

After a hard morning’s book-burning, the group moved on to Parliament Square. They waved placards and generated a few soundbites for Radio 1. Thus far, it is small beer. It may fizzle out. It may grow.